46 



Observations on the Structure of the Cornea op the Bee. 



By B. T. Lowne, M.R.C.S. 



{Read February 25th, 1870.) 



I have lately been engaged in making some sections of the cornea 

 of a large Carpenter Bee from South Africa, which have resulted 

 in my making out several very interesting points of structure. 



On referring to my account of the cornea of the fly,* you will find 

 I have described it as consisting of two layers — an external continuous 

 with the external layer of the integument, perfectly transparent, 

 and apparently structureless ; and an internal thicker layer, sculp- 

 tured into facets, or rather into numerous bi-convex lenses, set in 

 a hexagonal framework. This layer, which I believe is continuous 

 with the middle layer of the integument, is too thin in the fly for 

 its structure to be readily made out ; nor have I attempted to in- 

 vestigate it. 



The section which Mr. Hislop is kindly exhibiting for me is a 

 vertical section of the cornea of the Carpenter Bee already alluded 

 to, and I have found that it confirms what I have said regarding 

 the cornea of the fly. The external layer is far thicker than in the 

 fly, although it presents no trace of structure. It follows the con- 

 tour of the facets on the surface of the deeper layer. 



The deeper layer consists of numerous thin laminse, each being 

 composed of a vast number of parallel fibres. It further apj)ears 

 to consist of hexagonal prisms, vertical to the surfaces of the 

 cornea, and to the laminre of which it is composed. These prisms 

 are not, however, separable ; although the laminas and the fibres of 

 which they are composed are easily separated by treating the sec- 

 tion for a short time with a solution of caustic potash. 



The surfaces of this deeper layer of the cornea may be seen to be 

 covered with convex facets, a facet corresponding to either ex- 

 tremity of each vertical prism, the external facets being, however, 

 best marked. 



* Monograph on the Anatomy of the Fly. 



